1. Field of the Invention
The present invention relates to a bipolar pacing lead, and more particularly, to a bipolar screw-in pacing lead assembly having a tip electrode assembly comprising a cathode electrode defined by a metal ring and an anode electrode defined by a corkscrew shaped securing device which is adapted to be threaded into living tissue for securing the electrode assembly to the living tissue and at the same form an anode electrically connected to the living tissue.
2. Description of the Prior Art
Heretofore various pacing lead assemblies having screw-in devices or other securing devices for securing a pacing lead assembly to living tissue have been proposed. Examples of such previously proposed pacing lead assemblies are disclosed in the following patents or patent publications:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 3,253,595 Murphy, Jr., et al. 3,416,534 Quinn 3,472,234 Tachick 3,737,579 Bolduc 3,844,292 Bolduc 3,875,947 Jula, et al. 3,974,834 Kane 4,000,745 Goldberg 4,010,758 Rockland, et al. 4,026,301 Friedman, et al. 4,026,303 Babotai 4,046,151 Rose 4,106,512 Bisping 4,146,036 Dutcher, et al. 4,217,913 Dutcher 4,282,885 Bisping 4,311,153 Smits 4,357,946 Dutcher, et al. 4,381,013 Dutcher 4,452,254 Goldberg 4,463,765 Gold ______________________________________
The Murphy, Jr., et al. U.S. Pat. No. 3,253,595 discloses a cardiac pacer electrode system which includes two electrodes each having a projecting coil of platinum wire which can be inserted into a puncture wound made in a patient's heart.
The Quinn U.S. Pat. No. 3,416,534 discloses a body organ electrode which includes a helically wound conductor having a conductor tip which is sharpened to facilitate screwing into an organ which is to be electrically stimulated. The sharpened conductor tip is housed within the bore of a hypodermic needle so that once the needle has been inserted into the organ to be stimulated, the conductor is turned in order to advance the sharpened conductor tip into the organ tissue.
The Tachick U.S. Pat. No. 3,472,234 discloses a body organ electrode having a stiff helical sleeve positioned over an helically wound cable having a pointed tip and a key engageable, flattened conductor for facilitating screwing of the tip into an organ with a stylet.
The Bolduc U.S. Pat. No. 3,737,579 discloses a body tissue electrode and device for screwing the electrode into body tissue. The body implantable electrode comprises a flexible insulative conductor having a proximal end adapted for connection to a power supply and a distal end comprising an uninsulated, conductive, rigid helix adapted for attachment to body tissue. The device for screwing the electrode into body tissue is a tool which is cylindrically shaped and into which the insulated portion of the conductor is fitted so that the electrode comprising the rigid helix is securely held by the tool. Then, by applying a twisting rotation to the tool, the helical electrode may be screwed into the tissue.
The Bolduc U.S. Pat. No. 3,844,292 discloses an intravascular lead assembly having an electrically conductive barb at its distal end. The lead assembly is positioned within a cylindrical inner tube which, in turn, is positioned within a cylindrical outer tube and the lead assembly carried thereby is inserted into a body vessel. When the lead assembly is believed to be in a proper position in the heart, a plunger located at the proximal end of the lead assembly is depressed in order to move the inner tube and the lead assembly to a position where the barb just barely extends beyond an open end of the inner tube. Once it has been determined that the barb is in a satisfactory position, the plunger is further depressed in order to drive the barb a predetermined distance into the tissue of the heart.
The Jula, et al. U.S. Pat. No. 3,875,947 discloses a device for screwing a body tissue electrode into body tissue. The electrode is a rigid helical electrode which serves as the distal end portion of a conductor which may be screwed into body tissue. The electrode is screwed into body tissue with a device comprising a cylindrically shaped body which, once the helical electrode is positioned near the heart, is rotated in order to firmly screw the electrode into the heart.
The Kane U.S. Pat. No. 3,974,834 discloses a body implantable lead having a first electrode at its distal end comprising a rigid, electrically conductive helix with a sharp tip which is adapted to be screwed through tissue into a body organ and a second electrode which is in the form of a ring mounted on the lead just behind the first electrode. The lead has a bifurcated proximal end with each finger of the bifurcated end having a terminal pin extending therefrom.
The Goldberg U.S. Pat. No. 4,000,745 discloses an electrical lead for a cardiac stimulator and includes a helical member which may be screwed into the heart muscle. The electrical lead is attached or secured to the heart with an insertion tool comprising an elongated shaft having a beveled portion which is inserted between a turn in the helical wire and pushed into the electrical lead until the beveled end engages and grips a tapered portion of the lead.
The Rockland, et al. U.S. Pat. No. 4,010,758 discloses a bipolar body tissue electrode comprising a first helix-configured electrode adapted to be screwed into body tissue and a second disc shaped electrode disposed about the helical electrode for surface contact with the tissue. The first and second electrodes are connected to separate terminal pins in a bifurcated proximal end.
The Friedman, et al. U.S. Pat. No. 4,026,301 discloses an apparatus which includes a probe having a blunt, muscle-penetrating tip which is fitted with a sleeve so that the tip of the probe extends from the sleeve. A helical electrode is mounted on an elongated tool which is capable of imparting a rotational force to the electrode while allowing disengagement with the electrode in the direction of its longitudinal axis.
The Babotai U.S. Pat. No. 4,026,303 discloses an endocardial pacing electrode assembly comprising an electrode contained within a tube or casing and surrounded within the casing by a first spiral conductor which terminates at the distal end of the casing. A second spiral conductor is positioned surrounding the first spiral conductor and extends outside of the distal end of the casing to form a spiral pacing contact. The contact tip is not sharp, has no end points, and is round, continuous, and closes upon itself in a closed spiral configuration so that it can be screwed under the trabeculae or inner muscles of the heart without actually puncturing the heart.
The Rose U.S. Pat. No. 4,046,151 discloses a body implantable lead which has a stiffening stylet and which has a first helical electrode, a second ring electrode and two terminal pins in two proximal fingers connected respectively to the first and second electrodes in a manner as taught in the Kane U.S. Pat. No. 3,974,834.
The Dutcher, et al. U.S. Pat. No. 4,146,036 discloses a body implantable lead having a tissue securing member comprising a rigid, circular corkscrew or helix which extends beyond the end of a tip ring electrode in order to secure and maintain the ring electrode in engagement with endocardial tissue.
The Dutcher, et al. U.S. Pat. No. 4,217,913 discloses a body implantable lead and includes a helix or corkscrew which is electrically insulated from a electrode or electrically coupled to the electrode.
The Bisping U.S. Pat. No. 4,282,885 discloses an electrode assembly for implantation in the heart including an electrode lead and a helix protruding at the end of the electrode lead near the heart for screwing the electrode into cardiac tissue.
The Smits U.S. Pat. No. 4,311,153 discloses a screw-in lead having a lead tip with a sealing membrane through which a corkscrew electrode is rotated to engage heart tissue.
The Dutcher, et al. U.S. Pat. No. 4,357,946 discloses an epicardial pacing lead with stylet controlled helical fixation screw. The stylet controls a helical fixation screw in an electrode head of the pacing lead. The stylet is turned to advance the helical fixation screw laterally of the lead beyond the planar surface of the electrode head.
The Dutcher U.S. Pat. No. 4,381,013 discloses a removable stylet assembly comprising a first stylet portion including a straight wire with a curve at the distal end thereof, and a second stylet portion which is removable from the lead assembly and which includes a coil for transferring torque at the proximal end of the flexible coil to the distal end portion of the coil for implanting a corkscrew shaped electrode.
The Goldberg, et al. U.S. Pat. No. 4,452,254 discloses another form of screw-in tip electrode.
The Gold U.S. Pat. No. 4,463,765 discloses a pacing lead assembly, comprising a wire conductor extending within a tubular body and a corkscrew shaped securing device which is received in the tubular body and which has a proximal end fixed to a movable mounting member made of an insulative material in the tubular body. A drive mechanism in the form of a helical metal ribbon is received within the tubular body and extends from the proximal end of the lead to the distal end of the lead and is fixed to the other end of the mounting member. A terminal pin/drive member is positioned at the proximal end of the lead and has one end thereof connected to a proximal end of the ribbon and the other end thereof extending from the lead assembly. The terminal pin/drive member can be rotated to screw the securing device into living tissue in order to fix a separate distal electrode against cardiac tissue.
The West German Published Patent Application No. 28 06 069 discloses still another form of screw-in tip electrode.
As will be described in greater detail hereinafter, the bipolar screw-in lead assembly of the present invention differs from the various screw-in lead assemblies and similar lead attachment assemblies previously proposed by providing a tubular body having a distal electrode assembly at its distal end comprising a cathode electrode ring and an anode corkscrew shaped securing device which functions both as (a) means for securing the electrode assembly to the tissue of a heart and (b) means for establishing an anode electrical connection with the tissue. The anode electrode forming, corkscrew shaped securing device is electrically connected through a drive mechanism to an anode electrode ring in a single, finger-shaped, proximal terminal electrode assembly. A coiled wire conductor insulated from the drive mechanism is electrically connected to the cathode electrode ring at the distal end of the lead and to a terminal pin/drive member in the proximal electrode assembly which is adapted to be received in a terminal pin receiving socket in a pacer and which also can be rotated to drive the drive mechanism. The drive mechanism can be operated to rotate the corkscrew shaped securing device to secure the corkscrew securing device/anode electrode into cardiac tissue and at the same time place the cathode electrode ring against cardiac tissue in an electrically conductive manner. The terminal pin and the anode ring are received in and make electrical contact with electrical contact members in a socket in a pacer.